Load balancing using Round Robin multipathing policy on EMC VNX arrays

Products

• VMware vSphere ESXi

Issue/Introduction

In VMware vSphere ESXi version 5.1 and 5.5, the default Native Multipathing Plugin (NMP) Path Selection Policy (PSP) for VNX has changed from Fixed (VMW_PSP_FIXED) to Round Robin (VMW_PSP_RR). This change affects all supported VNX arrays. See the VMware Hardware Compatibility list for exact EMC models and firmware that support VMW_PSP_FIXED.

Environment

• VMware vSphere ESXi 5.1
• VMware vSphere ESXi 5.5

Resolution

After upgrading from ESXi 5.0.x to ESXi 5.1 or 5.5, all devices that were previously configured to use the Fixed PSP will be changed to the Round Robin PSP automatically. Devices managed by EMC PowerPath/VE are unaffected by this change.

 

Autorestore Capability on EMC Devices Managed by VMW_SATP_CX_ALUA and VMW_PSP_RR

• VMware vSphere ESXi 5.1/5.5 also includes an enhancement to the Round Robin NMP PSP, which allows to autorestore to the preferred (default) VNX storage processor (SP) after a fabric problem has been repaired. A fabric problem might include a failed HBA, NIC, CNA, switch, or SP front end port.
• In addition, VNX array software VNX Block OE version 05.31.000.5.726 and VNX Block OE version 05.32.000.5.006 contain an enhancement, which allows the Round Robin NMP PSP to autorestore to the preferred (default) VNX storage processor (SP) after that SP reboots. The reboot can be manual or caused by an array software upgrade.
• These enhancements and the change in default PSP from Fixed to Round Robin provide you with the benefit of multiple active/optimized paths for I/O scalability, as well as the benefit of autorestore to the preferred SP.

MSCS Configurations

Storage devices managed by the VMW_PSP_RR policy might result in unsupported configurations.